Guralp Systems CMG-DCM build <10,000 - Manual (Page 84)

Acquisition Modules and Platinum Firmware Networking Configuration
7.3.1.2 VLAN Static IP
If DHCP is not being used, the IP address text field should be populated with
the required address in CIDR format, where the address is followed by a slash
and then the number of bits defining the netmask, e.g. 192.168.0.1/24 for
IPV4 or 2001:db8:/32 for IPV6.
For more information about CIDR, please refer to
http://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing .
The Default route (gateway) field should be populated with the IP address of
the default router for this VLAN. If more complicated routing configurations
are required, these can be entered in expert mode.
7.3.2 Configurable parameters in expert mode
A set of additional parameters are available when in expert mode. These are
identical to the additional parameters on the physical interface configuration
screen, as described in section 7.1.2 on page 72 and are not discussed further
here.
7.4 Network Time Protocol (NTP)
The Network Time Protocol (NTP) is a method of synchronising the clocks of
computer systems over networks, including those with variable latency, such
as packet-switched networks. Platinum firmware include a fully-featured
NTP implementation, which can be used to keep the system clock
synchronised to external time sources, such as Internet NTP servers,
connected digitisers and connected GPS receivers.
Most acquisition modules include a battery-backed real-time clock (RTC)
module which can retain system time with tolerable accuracy during periods
of power loss. CMG-DCMs will revert to January the 1 st , 1970 after each
power-cycle.
The system clock is used to provide time-stamps for log-file messages and can
also be used to generate NMEA and PPS signals, emulating a GPS receiver, in
MAN-EAM-0003 84 Issue E - February 2014